: This retrospective study used cone beam computed tomography CBCT to evaluate various radiographic prognostic indicators that affect the outcome of root canal retreatment. The study population was selected from consecutive patients examined in the endodontic department from June 1 to December 31, 2013. In total, data were collected for 143 patients mean age 47.7 years ; female : 89, male : 44 who underwent CBCT examination, including 276 roots with periapical radiographs of 158 teeth. CBCT images were re-interpreted independently by one oral radiologist for cases of periapical root resorption and periapical hypercementosis. Nonsurgical endodontic retreatment was indicated for 125 roots, and was subsequently performed by one of four certi ed endodontists. Each case was followed up and the prognosis was assessed in October 2014. Of 125 root canal-treated cases, 96 were deemed to have a satisfactory prognosis, 27 were considered questionable and 2 were considered unsatisfactory . In the 96 satisfactory cases, 15 showed periapical hypercementosis, and 51 showed periapical root resorption. The chi-squared test was used to analyze differences between groups. A value of P 0.05 was considered signi cant. There was a signi cant difference in the prognosis between the hypercementosis cases and the other groups. Several studies suggest that the presence of root resorption may worsen the prognosis of endodontic treatment. In this study, the presence of root resorption did not affect prognosis. This study provides evidence that CBCT is helpful in evaluating the prognosis of endodontic retreatment cases.